It looks like it could be thread algae. I have a marimo ball and three types of moss will those out compete it ? I remove it when ever I see it.

I don't think a Marimo ball will do it. When I say out compete, I mean it will take up nutrients faster than the algae would, I don't think a marimo will have the capability since they are insanely slow growing. Since your tank is set up for low tech, why not look at some low light plants?